DESCRIPTION Demography of ancient human populations is studied using variation at microsatellite, or short tandem repeat (STR) loci in lineages marked with single nucleotide polymorphisms (SNPs). Each SNP lineage is stochastically growing or declining in size and dividing into sublineages following population subdivision. Within-lineage STR variation reflects these demographic changes and carries signatures of the ancient events whose time can be estimated. The research falls into three areas. The first will focus on estimators of divergence and expansion time based on the variance, kurtosis and other higher moments of repeat scores at microsatellite loci. Dynamic models will be studied that do not assume mutation-drift equilibrium for microsatellite variation, and will include gene flow and various types of population processes. The second area includes estimation of microsatellite mutation parameters, such as the variance and other statistical moments of mutational changes in repeat score, between-locus variation in mutation rates, mutational bias, etc., that are important for estimating historical events using microsatellite polymorphisms. The analysis will be based on statistical and dynamic models of the mutation distribution and will use available data from studies on microsatellite mutation rate and population data. The third area extends the Parent Program Project to include previously collected samples from Siberia (Burjats, Tuvinians, Yakuts, Evenks, Chukchis, Eskimos) in order to study further the peopling of the New World from Northeast Asia. The application of the estimators from the first two areas to existing and newly obtained data will permit more precise dating of the migrations into North America. It will also augment information at the Stanford DNA database on human worldwide populations. The proposal will further strengthen the productive scientific cooperation between the collaborating U.S. and Russian geneticists that has existed for almost ten years and has produced about 30 peer-reviewed publications while also involving other scientific groups from the United States, Sweden, Denmark and Australia.